Selective transfer device for microwave energy



April 1, 1958 KIY ToMiYASU 2,829,347

SELECTIVE TRANSFER DEVICE FOR MICROWAVE ENERGY Filed June 13, 1956 5Sheets-Sheet l INVENTQR K/Yo TOM/msu April r1, 1958 KlYo ToMlYAsu ySELECTIVE TRANSFER DEVICE. FOR MICROWAVE ENERGY Filed June 13, 1956 5sheets-sheet 2 INVENTOR ATTORNEY April 1, 1958 KlYo 'roMl'YAsu SELECTIVETRANSFER DEVICE FOR MICROWAVE ENERGY Filed June 13, 195e 5 Sheets-Sheet5 INVENTQR /Yo TOM/msu l ATTORNEY April 1, 1958 KlYo ToMlYAsU 2,829,347

sELEcTIvE TRANSFER DEVICE FoR MICROWAVE ENERGY Filed June 13, 1956 5sheets-sheet 4 iNvENToR /BfQ/ 0'7b/w YASU l i@ M April 1, 1958 KlYo'MlYAsU 2,829,347

SELECTIVE TRANSFER DEVICE RoR MICROWAVE ENERGY Filed June 15, 195e 5sheets-sheet 5 qfll #M [20 /Z 4/7 IC'- l El l INVENTOR /Bl//Yo 75M A50ATTO RN EY Unite sntncrivn TRANSFER DEVICE Fon Mrcnowava ENERGYAppucaaaa :ame is, 1956, serial No. 592,231

in ciaims. (ci. ssa- 7) The present invention relates to waveguideapparatus for microwave energy, and is particularly concerned withenergy transfer apparatus for selective transfer of energy between aplurality of waveguides. This application is a continuation-in-part ofU. S. patent` application S. N. 213,276, by K. Tomiyasu, filed February2l, 1951.

An object of the invention is to provide improved microwave energy pathcontrol apparatus.

More specifically, it is an object to provide improved apparatus forselectively transferring energy from one waveguide to another, and forcontrol of the energytransfer.

A further Objectis to provide improved apparatus for receiving microwaveenergy through one waveguide and selectively routing it through one oranother of plural output waveguide routes.

Another object is to provide improved apparatus for receiving microwaveenergy through one waveguide and selectively routing it through one andonly one of a plurality of output waveguides. l

Yet another object is to provide a compact, improved structure forvariable directive coupling between first and second waveguides.

These objectives are met by providing two waveguides xed in adjacentpositions with respective waveguide sections thereof parallel, andproviding registering openings in the adjacent walls of the parallelkwaveguide sections for energy transfer therebetween.

These openings are made of such breadth and length as to providecomplete directional transfer of the microwave energy from one of thewaveguides to -the other, inV accordance with the principles of patentapplication Serial No. 197,064, filed November 22, 1950, in the names ofKiyo Tomiyasu and Seymour B. Cohn:

A movable shutter area of conductive'material is interposed between theguides to obstruct the region of communication therebetween, e. g. tototally block the registering openings and to insure confinement of anenergy component arriving in one of the two waveguides to continuance ofpropagation in that waveguide. The shutter element is arranged in such away as to be shiftable to unblock the area of said openings, wholly orpartially, and to bring about transfer of all or a substantial part ofthe microwave energy from one waveguide to the other, or from eachsupplied waveguide to each other.

Representative embodiments of the present invention are illustrated inthe drawings.

`Fig. 1 is a perspective View of an energy path control apparatusarranged to serve effectively as a double-throw switch mechanism, fortotal retention of energy in one wave guide, or for total transfer ofenergy-thereformf to the other of the two waveguides;

Fig. 2 is a longitudinal sectional'view of the of Fig. l, taken on theline 2 2 in Fig. 3;

Fig. 3 is a cross-sectional view of the structure of Fig..1 taken on theline 3--3 in Fig. 2;

Fig. 4 is a fragmentary cross-sectional view illustrating structure I 2the same structure as shown in Fig. 3 but with the shutter elementpositioned for total energy transfer from one waveguide to the other;

Fig. 5 is a plan View of a longitudinally adjustable 5 shutterembodiment of the present invention, parts being broken away and partsshown in section, for clarity of illustration;

Fig. 6 is a side elevation of the embodiment of Fig. 5, parts likewisebeing broken away for clarity of illustration;

Fig. 7 is a drawing of a modification of the shutter 15 of Figs. 1-4; lFig. 8 is a plan view of a multi-circuit switching struc ture embodyingthe present invention;

Fig.- 9 is a cross-sectional View of the structure of Fig. 8, taken onthe line 12-12 therein; Fig. 10 is a perspective view, partly incross-section, of a modified multi-circuit switching structure embodyingthe present invention;

Fig. 1l is a cross-sectional view, partly broken away, looking up at thestructure of Fig. 10; and

Fig. 12 is a cross-sectional view, partly broken away, of the structureof Fig. 11.

The embodiment illustrated in Figs. 1-4 basically ini cludes a firstwaveguide 11 and a second waveguide 13 rigidly fixed together, withsections of appreciable length in the respective waveguides 11 and 13positioned parallel and adjacent to each other. Registering openings areprovided in the adjacent walls of the respective sections of waveguides11 and 13, and a shutter element 15 is ar- -ranged for transversesliding movement between these sections of waveguides il and 13.

The slide or shutter element 15 is provided with a longitudinal opening17, so located that the shutter 15 may be moved to a position at whichthe opening 17 is situated directly between the parallel and adjacentsections of waveguides i1 and 13, permitting energy communication fromone of the two guides to the other through the openings therein.

The openings in the waveguides and the opening 17 in shutter 15 are soarranged that when the shutter opening and the waveguide openings are inregister, complete directional energy transfer occurs through theopenings, from one waveguide to the other. When the slide element 15 hasbeen moved to the position with opening 17 re"- mote from the openingsin the parallel waveguide sections, the passage between the waveguides11 and 13 is closed, and accordingly any energy supplied to one end ofone waveguide proceeds directly therethrough to the other end thereofwith substantially complete freedom from energy transfer over to theother waveguide. The shutter or slide element 1S is illustrated in Figs.1, 2 and 3 as positioned for this Zero-transfer condition.

The construction chosen for the embodiment illustrated in Figs. 1 4involves rectangular tubing sections at thc ends ofthe waveguides 11 and13, the relatively long parallel middle sections of the waveguides 11and 13 being made up as a composite structure including iirst andsecondside plates 21 and 23, upper and lower intermediate longitudinalpieces" 2S and 27, and partition elements 29 and 3l (Fig. 2). The insidesurfaces of said plates 21 and 23, in the space betweenthe left-hand andright-hand rectangular 'tubular portions of the waveguides as seen inFigs. 1 and 2, serve as the interior side wall surfaces of the twowaveguides. The upper and lower intermediate pieces 25 and 27 serve notonly to afford a mechanically rigid assembly with the side plates 21 and23, but also, these pieces serve as continuations of the narrow wallsurfaces of the respective waveguides, between the left-hand rectangulartubing sections and the righthand rectangular tubing sections,

j' 2,829,347 r f Y Partition velement 29 shown in Fig. 2 Serves simultaineously as a portion of the lower interior wall surface of the upperwave guide 11., and a portion of the upper interionwall surface of thelower waveguide 13, reaching to`v the left-hand ends of the openings 33and 35 in the upper and lower waveguides 11' and 13, respectively.Similarly, partition element 31 serves as an extension of the adjacentnarrow interior wall surfaces of the wave guides, between the ends ofthe right-hand rectangular` tubing sections of waveguides 11 and 13 andthe righthand ends of the openings 33 and 35.

The shutter4 15 is supported-at its left edge in milled conformal slots37 in the side plates 21 and 23 and partition element 29 and at itsright edge, similarly, Vin milled conformal slots 39 inthe side yplates21' and 273 and partition element31. These slots accurately positionshutter 15 and act as guides for the transverse sliding movement jthereof.

Extensive recesses are milled in the middle region of said plates 21 and23, in such a Way as to leave anges extending along the regions thereofadjacent the operating location of shutter 15. These flanges areprovided with a. series of transverse cuts, in such a Way as to formthem into serrated chokes 22, 2 4, 26 and 28, each comprising a seriesof transversely extending tines parallel to and spaced slightly from thesurface of shutter 15.

The length of the tines of the serrated chokes 22, 24, 26 and 28 ispreferably of the order of one-fourth wavelength, and the width andspacing between tines and spacing of the tines from the shutter 15 arepreferably much smaller than one-fourth wavelength. As an example, threeor more tines may be included within a disance of one-fourth wavelengthalong the serrated choke (i. e., transverse the direction of extensionof the tines).

Such serrated chokes per se are described and claimed in U. S. patentapplication Serial No. 197,063, filed No# vember 22, 1950, in the nameof the present inventor.

The rectangular tubing sections of the ends of the waveguides preferablyare recessed within the ends of `the composite assembly formed ofelements 21 2,3,` 25,

ings 33 and 35 in the respective wage guides 11 and 13 are appreciablylonger than the opening 17 in shutter 15. Accordingly, the length of theopening 17 determines theeffective length of the region of intercouplingbetween the waveguides 11 and 13 when the shutter is in the positionillustrated in Fig. 4 for permitting energy trans-k y fer between guides11 and 13. This effective length of the region of communication is ofconsiderable importance to the operation of the structure; and for agiven operating frequency, and giveninternal dimensions of the waveguides 11 and 13, this length of opening 17 may be arranged to providecomplete energy transfer from one waveguide to the other with retentionof directional energy transmission. With a greater or lesser length ofthe opening, partial energy transfer is accomplished betweenthewaveguides, with maintained direction of transmission, the incidentenergy beingthus divided intoY la transferred component and a componenttransmitted onward through the guide through which it arrived. Thus, ifthe structure is to serve primarily as a transfer switch system, theopening 17 must be made to be of that length which provides 100% energytransfer.

The principles of operation of this'type of coupler systemare closelyrelated to thosevsetforth `in, detailin patent application Serial No.1973064, filed` November 4 22, 1950, in the names of the presentinventor and Seymour B. Cohn as joint inventors.

As explained in the application above referred to, the operation of thistype of coupler system involves the consideration of two modes of waveenergy propagation which prevail in the mutually adjacent waveguideportions whose interiors are exposed to each other through thelongitudinally extensive openings in the respective guides. It isVcustomary to design a rectangular waveguide for efficient transmissionof energy` of a known frequency, the mode of transmission being afundamental mode of the guide usually lreferred to as the TELO mode.This is the dominant transverse electric mode. The a" dimension of thesimple rectangular waveguide ordinarily is such as to prevent it fromtransmitting energy of this frequency in any of the known higher modes.

When two of such waveguides are juxtaposed with their narrower wallsmutually adjacent, and these adjacent narrower walls are openedthroughout an appreciableflongitudinal extent, the effect is tosubstantially double the a dimension'of this waveguide portion. Thiseffectively enlarged waveguide portion is then capable of. supportingenergy in two modes of propagation, the first being closely related tothe simple transverse electric mode TELO described in connection withthe basic waveguide section, and the second mode being the asymmetricalmode designated TEM. If inductive loading is provided as by the use of aseries of spaced cross-bars each extending across the opening in one ofthe waveguides (or across the opening in the shutter element), suchlinductive loading brings about a departure of the symmetrical mode fromthe normal character of a TEU, energy distribution in the enlargedwaveguide section.

Whether or not inductive loading is provided, the symmetrical mode andthe asymmetrical mode are propagated along the doubled waveguide sectionat different phase velocities. At the point of entrance of the energyinto the doubled wave guide section, they are in phase in the lowerguide (i. e., in waveguide 13),assuming this guide only is supplied withenergy yat its left-hand end, as by a source S2. At the point ofentrance into the doubled waveguide section,V these components are inphase opposition in the upper waveguide (waveguide 11). Farther alongthe doubled waveguide section, however, the two components approachcophasality in the upper guide, even as they approach Vphase oppositionin the lower guide. If the effective length of the opening between theguides is sufficient, complete energy transfer takes place from thelower guide' to the .upper guide with unidirectional propagation beingmaintained, away from the source end (S2) and toward the opposite end ofthe structure, i. e., toward the right-hand end of wave guide 1'1.

` If the effective length of the openings is less or greater than thelength for complete energy transfer, then the energy will be divided,part ofA it being transferred and proceeding outwardV toward theright-hand end of waveguide 11 to' utilization device U1, the remainingpart of the incident energy from source S2 being retained in waveguide13 and delivered to` utilization device U2.

p If inductance cross-bars are provided across the opening in oneV ofthe waveguides, or across the opening 17 in shutter 15', asillustratedin Fig. 7, the effective length of the opening for complete energytransfer from one guide to the other must be appreciably greater, forexample, three times greater than the effective length of the openingwhere, no cross-bars are employed. Y

If desired, energy from. two or more sources may be handled by thestructure shown in Figs. l-4 simultaneously, For. example, a source S1may be coupled to the left-hand end ,of waveguide 11 and a source S2 mayconcurrently supply energy tothe left-hand end of waveguide 13.` Thesesources needy not be 4of equal frequencies, nor need they be speciallyrelateda's to theirl amplitudes. It is only` necessary that theirfrequencies bevvithin the design lfrequency. range of operation of thestructure." With the shutter positioned in such a way as to completelyblock the openings, as shown in Figs. 1 3, al1 of the energy from sourceS1 proceeds directly through to utilization device U1, and all of theenergy from source S2 proceeds directly through waveguide 13 toutilization device U2.

A shift of the shutter to situate the opening 17 directly between thewave guides 11 and 13, as illustrated in Fig. 4, brings about a completeinterchange of the communication circuits, so that the energy fromsource S1 is then delivered to utilization device U2 and the energy fromsource S2 is delivered to utilization device U1. Because of theappreciable longitudinal distribution of the coupling between waveguides11 and 13, the transfer of energy proceeding from source S1, over towaveguide 13, is accomplished with negligible leftward propagation(towards source S2), and likewise, the transfer of energy proceedingfrom source S2, over to waveguide 11, is accomplished with negligiblepropagation in waveguide 11 toward the left-hand end thereof.

Typical dimensions for an operating frequency of 10,000 megacycles persecond are as follows:

Inches Width (I. D.) of each waveguide 0.40 Height (I. D.) of eachwaveguide 0.90 Width of waveguide openings 0.40 Width of opening 17 inshutter 15 0.40 Length of waveguide openings 3.9 Length of straightsides of opening 17 2.62 Length of opening 17 3.0

The waveguide walls extend close to the surface of the shutter 15, butare slightly spaced therefrom, substantially equally as the tines of theserrated chokes are spaced from the shutter, as is clearly seen in Fig.3. Preferably, for providing maximum continuity of transmission throughthe wave guides and avoiding small energy reflection componentsy whichcould result from the effectively increased a dimension from the lowersurface of piece 25 down to the upper surface of shutter 15, and thesimilarly increased a dimension from the .upper surface of piece 27 tothe lower surface of shutter 15, it is desirable to provide alongitudinally extensive boss or plate on each of pieces 25 and 27coextensive with the waveguide openings 33 and 35, and of thicknessequal to or slightly less than one-half the thickness ,of partitionelements 29 and 31.- By this arrangement, the effective "a dimensionthroughout each waveguide is substantially uniform when the shutter 15is positioned as shown in Fig. 3 for preventingH energy transfer betweenthe two waveguides.

' By making the length of the openings in the waveguides appreciablygreater than the effective length for full energy transfer, an advantageof simplified construction is realized in that the constructor isenabled to make anexperimental opening 17 in shutter 15, and if suchopening proves to be of insuicient length, it may be extended by arelatively simple machining operation, or a series of operations, untilthe desired result is obtained. Similarly, for a given set of waveguides 11 and 13, various shutters with, different lengths of theopenings maybe providedr for complete energy transfer at a plurality ofrespective wave lengths, or on the other hand, openings of variouslengths in the shutters may be provided for various amounts of energytransfer. f

In the embodiment shown in Figs. 5 and 6, upper and lower waveguides 111and 113 areriixed together as by structural elements 118 and 119, and anelongated shutf ter 115 is provided for longitudinal adjustment of itsposi? tion between the elongated parallel sections of waveguides 111 and113.

Serrated chokes 122, 124, 126, 12S are provided for affording theelectrical effect substantially equivalent to direct junctions betweenrshutter 115 and the walls of the upper and lower waveguides, without therequirement` of direct friction contact, and for preventing thev escapelof energy from the. confinement within the waveguides.

The elongated shutter is guided in suitable grooves therefor in thestructural elements 118 and 119, and is slightly spaced from the tinesof the serrated chokes 122, 124, 126, 12S and from the adjacent edges ofthe Waveguides 111 and 113.

Matching openings 133 and 135 are provided in waveguides 111 and 113,respectively, and an opening 117 which may be of similar configurationand of equal size, if desired, is provided in the shutter 115.

These openings are so situated that the shutter 115, shown set for aposition of partial power transfer, may be moved to the right to aposition of full register of the three openings, for full transfer, ormay be moved to the left to-a position completely preventing energytransfer from one waveguide to the other.

It is not essential for the length of the opening in the shutter to beexactly equal to the length of the openings in the waveguides since inany event the performance of the system is determined by the length ofthe effective opening for a given shutter setting.

It will be readily appreciated that the embodiment of Figs. 5 and 6 isusable in the same ways in which the embodiment of Figs. l-4 may beused, for providing Aparallel transmission or crossed-over transmission,in two simultaneous communication paths, if desired. The structure ofFigs. 5 and 6, however, has the additional feature that the degree ofenergy transfer may be continuously varied from the condition ofsubstantially complete transmission directly through one waveguide (orin parallel paths through the parallel waveguides), to the condition ofcomplete power interchange between the waveguides. This structure ofFigs. 5 and 6 is thus suitedfor all of the applications for which thecoupler of U. S. patent application Serial No. 197,064 is suited.

If desired, a scale of calibrations 149 may be provided on the shutter115, for indicating the degree of power transfer in percentages, or indecibels, or on such other calibration basis as may be desired.

One of the elongated openings in the waveguides or in the shutter may beprovided with a loading element or elements such for example asinductance cross-bars, if desired, as described above in connection withthe embodiment of Fig. l.

The structure illustrated in Figs. 8 and 9 is a selective microwaveenergy transfer structure involving the same operating principles as inthe previous embodiments, but with a ring-like physical arrangement foremployment of a rotary shutter system 315, the principal wave guidesystem 311being curved into an incomplete ring transmission path. Asecond waveguide 313 is rigidly positioned above a portion of waveguide311 and is arcuately conformal therewith over a portion of its length. i

Registering longitudinally extensive openings are provided through theupper interior surface of waveguide 311and the lower interior surface ofwaveguide 313 for permitting full energy transfer from waveguide 311 towaveguide k313, with directional transmission main-v tained, to conveysubstantially the entire energy fed into waveguide 311 through flange361 thereof, out through waveguide 313 and flange 365 thereof. Suchcomplete energy transfer occurs through the registering openings ofwaveguide 311 and waveguide 313 when rotary shutter 315 is so positionedas to leave these openings totally unblocked.

A plurality offurther wave guides 373 and 375 are similarly rigidlypositioned above waveguide 311, and arranged withlongitudinallyextensive openings adjacent to similar registering openings in waveguide311.

A spider frame including a hub 380 and arms 381, 383, and 385 may beprovided for supporting the shutter bearing and for lending rigidity tothe system. The

upper waveguides 313,` 373 and 375 are supported on 7 brackets 387, 389and 391, respectively, extendingupf ward from waveguide 311. Thesebrackets may, 1f desired, comprise extensions of the spider arms 381,383

and 385.

Serrated chokes typied by chokes 392 and 393 are provided on waveguide311, over arcuate regions there` of including and extending beyond thelongitudinally extensive openings therein; and corresponding serratedchokes are provided along the sides of the arcuate portions ofwaveguides 313, 373 and 375, the spacing between the lower waveguidechokes 392, 393 and the chokes of the upper waveguides being slightlygreater than the thickness of the shutter 315.

The clockwise end of waveguide 311 beyond the ends ofthe registeringopenings of waveguides 311 and 375 is provided with an energy absorbersuch as a filling of high-loss dielectric material.

With the shutter 315 positioned as illustrated in Fig. 8, blocking thecommunication path through the registering openings of waveguides 311Land 313, energy entering waveguide 311 at flange 361 is conveyed aroundto the registering openings of waveguides 311 and 373,` and transferredfrom waveguide 311 to waveguide 373 through these openings, andtransmitted outward through flange 374. The registering openingsofwaveguides 311 and 375 are blocked when the shutter 315 is positionedas seen in Fig. 8, but this is only incidental, since substantially noneof the energy supplied through flange 361 remains untransferred andproceeds in waveguide 311 be-r yond waveguide 373.

Assuming the shutter 315 rotated 120 clockwise from the position seen inFig. 8, the regions of communication to waveguides 313 and 373 areblocked, and the energy fed into4 waveguide 311 proceeds on around tothe proceeding clockwise through waveguide 311 first encounters apartially opened transfer system, because this results in partialtransfer of the energy through such a transfer system, and completetransfer of the energy through the next open transfer system encounteredby` the energy continuing clockwise in waveguide 311. For example,assume shutter 315 rotated 90 clockwise from its position illustrated inFig. 8. As thus repositioned, the shutter would entirely block theregistering openings of waveguide 311 and 313, and would reduce by substantially half the effective length of the window or passage comprisingthe registering openings of waveguides 311 and 373. A partial energytransfer into waveguide 373 would result, the remaining energyproceeding onward in the clockwise direction in waveguide 311, and allbeing transferred out through fully open waveguide 375.

Like operation prevails if the shutter is so positioned as to block theregistering openings of waveguides 311 and 375, and partially unblockthe registering openings of waveguides 311 and 313. Such a position isobtained if the shutter 315 is displaced a few degree counterclockwisefrom the position illustrated in Fig. 8.

With the arrangement of the shutter 315 and the openings as illustratedin Fig. 8, there is always at least one fully open area of communicationbetween waveguide 311 and another waveguide, and hence the powerentering at ange 361 is always communicated to one or at most two of theoutput waveguide ends.

As in all of the previous forms` of the invention, the source and loadconnections .readily may be interchanged, a load device at ange 361being supplied by one or another of the respective sources'connected toguides 313,

' sponding opening 435, 437 or 439.

373 and 375, or by microwave power contributions from f selectivemicrowave energy transfer structure involving operating principlessimilar to those of the structure of Figs. 5 and` 6. The structure ofFigs. l0, ll, 12 differs from the structure of Figs. 8 and 9 in thatenergy is transferred from the principal waveguide system to one andonly one of the output waveguides. The principal waveguide systemconsists of a waveguide section 411 formed into arcuate shape about acentral axis. Waveguide section 411 comprises an annular member 418 andan annular channel member,419. Flanges of annuiarchannel member i519 arejoined as by bolting or welding to annular member 418 to form waveguidesection 411. A pluralityy of secondary waveguide sections 413, 415, and417 are rigidly positioned and tixed to waveguide section 411. Secondarywaveguide sections 413, 415, and 417 comprise separate portions of anarcuate waveguide section formed by an annular member 420 and an annularchannel member 421. Outwardly projecting flanges on annular members 418and 420 are joined together to form a rigid structure, whereby planesurfaces 425, 427 of respective channel members 419, 421 are disposedadjacent, but not in contact with each other.

Electromagnetic energy is coupled into waveguide sec tion 411 by meansof an input waveguide section 423 which projects into an opening in thewall of each of members 418, 419 of waveguide section 411. Energycoupled into waveguide section 423 travels counter-clockwise inwaveguide section 411 as viewed in Fig. 1l. The extremecounter-clockwise end of waveguide section 411 is terminated in anon-reilective dissipative termination 424. Electromagnetic energy isreceived from secondary waveguide sections 413, 415, 417 by means ofrespective output waveguide sections 426, 428 and 430. Each of sections426, 428, 430 is coupled to its corresponding secondary waveguidesection through openings in the walls of members 420, 421. The extremeclockwise end of each of secondary waveguide sections 413, 415, and 417of Fig. 11 is terminated with respective non-reflective dissipativeterminations 431, 432, and 433.

Arcuate openings 435, 437, 439 are provided through the plane surface425 of waveguide section 411 and the :adjacent plane surface 427 ofsecondary waveguide sections 413, 415, 417 for permitting energytransfer from waveguide section 411 to any one of'waveguide sections413, 415, and 417. Openings 435, 437, and 439 are of equalarcuateextent. The arcuate spacing between these openings should be at least asgreat as the arcuate.

extent of said openings. This is necessary in order that energy becommunicated from waveguide section 411 to only one of secondarywaveguide sections 413, 415, and 417.

A shutter 441 is supported for rotation between adjacent surfaces 425,427 n milled slots in the abutting anges,

of annularmernbers 418 and 420. Shutter 441 is provided with an opening442, the arcuate extent of opening 442 being equal to the length of anopening necessary to provide 100% energy transfer between waveguidesection 41,1 and one of sections 413, 415 and 417.' In Fig. 11 shutteropening 442 is shown in registration with opening 437. Electromagneticenergy is transferred from waveguide section 411 to one of waveguidesections 413, 415, and 417 when opening 442 registers with the corre-When no portion of opening 442 is opposite openings V435, 437 or 439,all of the energy supplied section 411 from input section 423 istransferred to termination 424 where it is dissipated. In this manner,energy is delivered to only one of output waveguide sections 426, 428,and 430,k or is delivered to termination 424. In no instance is theenergy delivered simultaneously to two output waveguide sections. A

`generator delivering energy to input waveguide section 423 'alwaysfeeds almatched load, either a load at the end of one of the outputwaveguide sections 426, 428, 430 or termination 424. Consequently, thereare no switching transients or reflections introduced in the sys-Y tem.

`Serrated chokes, such as chokes 444 and'445 are providedforaording theequivalent of electrical contact between shutter 441 and the adjacentwalls of the upper and lower waveguide sections to preventv escape ofenergy between the shutter and the waveguide sections and to preventcoupling between the waveguide sections other than lthrough shutteropening 442.

' The length of the openings 43S, 437, and 439 may be made longer, andcorrespondingly opening 442, by the employment of inductance cross-bars447 disposed along openingv 442. An indicator 448 may be employed toshow the'position of the shutter opening. Holes 449 may be utilized incooperation with a cog wheel, not shown, for moving the shutter opening442 from registration with one of openings 435, 437, and 439 toregistration with another of said openings.

While the arcuate extent of opening 442 should be that required totransfer 100% of the energy from waveguide section 411 to one ofsecondary waveguide sections 413, 415 and 417, the arcuate extent ofopenings 435, 437 and 439 may be equal to or greater than that ofopening 442. However, the arcuate spacing between openings 435, 437 and439 should be equal to or greater than the arcuate extent 4of opening442. This is necessary in order that energy be transferred to only oneof the secondary waveguide sections. In order to provide the smallestpossible structure, it is preferable that the length of openings 435,437 and 439 be made exactly equal to the arcuate length necessary for100% coupling, and that the length of the arcuate spacing between theseopenings be made the same arcuate length.

As in all of the previous forms of the invention, the source and loadconnections may be readily interchanged.

Since many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Selective microwave power transfer apparatus comprising rst andsecond waveguides respectively including first and second substantiallyadjacent wall surfaces, wherein said first waveguide is formed as an arcabout a predetermined axis to guide energy therein along a pathcorresponding to a portion of a circle, said first and second waveguidesbeing rigidly fixed together and said first and second surfaces havinglongitudinally extensive registering openings therein through which theinterior of said first and second waveguides are exposed to each other,said rst waveguide including at least one longitudinally extensiveopening in said first surface in addition to the opening thereincommunicating with said second waveguide, and shutter means ofconductive material movable substantially along said Walls forselectively blocking or unblocking the region of communication betweensaid first and second waveguides for controlling the transfer ofmicrowave power between said first and second waveguides, said shuttermeans comprising a rotatable shutter supported for rotation about saidaxis and having a conductive area interposable between said first andsecond waveguides according to the angular position of said rotatableshutter.

2. Selective microwave power transfer apparatus as defined in claim l,further including at least one further waveguide adjacent saidadditional opening in said rst surface of said first waveguide, andhaving a further opening therein in register with said additionalopening in said first surface of said first waveguide, said shutterconductive area being selectively interposable between said firstwaveguide and said further waveguide.

3. A waveguide switching apparatus comprising a first waveguide sectionadapted for propagating electromagnetic waves along a first axis, saidwaveguide section v10 having at least one substantially plane wallparallel to said first axis, said plane wall having at least two-openings extending parallel to said first axis, wherein said firstwaveguide section is formed into arcuate shape about a second axisperpendicular to a plane including said plane wall; further waveguidesections each adapted for` propagating electromagnetic waves alongfurther cor-k responding axes, each of said further waveguide sectionshaving at least one substantially plane wall parallel to thecorresponding axis thereof, the plane wall of each of said furtherwaveguide sections having an opening 'ex-, tending parallel to thecorresponding axis of said waveguide section, said further waveguidesections being rigidly fixed with respect to said first waveguidesection, wherein the opening in the plane wall of each of said fur ierwaveguide sections registers with an opening in the plane wall of saidfirst waveguide section, and whereby said first waveguide sectioncommunicates with each of said further waveguide sections; and asubstantially plane conductive shutter perpendicular to and adapted forrotation about said second axis, said shutter being further disposedfrom movement between the registered openings of said further waveguidesections and said rst waveguide section, whereby said shutterselectively blocks communication between said first waveguide sectionand said further waveguide sections.

4. A waveguide switching apparatus as in claim 3 wherein the plane wallof each of said further waveguide sections is disposed parallel to theplane wall of said first waveguide section and at least the portion ofeach of said further waveguide sections containing said opening isformed into arcuate shape about said second axis, the radius ofcurvature of said arcuate shape being equal to the radius of curvatureof said first waveguide section.

5. A waveguide switching apparatus comprising a first waveguide sectionadapted for propagating electromagnetic waves along a first axis, saidwaveguide section having at least `one substantially plane wall parallelto said first axis, said plane wall having at least two openings ofequal extent parallel to said first axis, wherein said first waveguidesection is formed into arcuate shape about a second axis perpendicularto a plane including said plane wall; further waveguide sections eachadapted for propagating electromagnetic waves along furthercorresponding axes, each of said further waveguide sections having atleast one substantially plane wall parallel to the corresponding axisthereof, the plane wall of each of said further waveguide sectionshaving an opening extending parallel to the corresponding axis of saidwaveguide section, the extent of the openings of said further waveguidesections being substantially equal to that of the openings of said firstwaveguide section, said further waveguide sections being rigidly fixedwith respect to said first waveguide section, wherein the opening in theplane wall of each of said further waveguide sections registers with anopening in the plane wall of said first waveguide section, and wherebysaid first waveguide section communicates with each of said furtherwaveguide sections; and a substantially plane conductive shutterdisposed perpendicularly to and adapted for rotation about said secondaxis, said shutter having an opening of arcuate extent not greater thanthe arcuate spacing between said first waveguide openings, whereby saidshutter selectively blocks communication between said frst waveguidesection and said further waveguide sections.

6. A waveguide switching apparatus comprising a first waveguide sectionformed into arcuate shape about a predetermined axis to guideelectromagnetic energy therein along a path corresponding to a portionof a circle, a plurality of arcuate openings in the wall of saidwaveguide section and spaced along said path, said path spacing beingnot less than a predetermined minimum value; a plurality of secondwaveguide sections, each of said second waveguide sections having anopening in the wall thereof of arcuate extent no less than saidpredetermined minimum value and being rigidly fixed with respect to saidfirst waveguide section, wherein each of the openings in said secondwaveguide sections registers with an opening `of said first waveguidesection; and a conductive shutter adapted for rotation about said axisand disposed for movement between the registering openings of saidsecond waveguide sections and said rst waveguide section, said shutter`having an opening of arcuate extent equal to said predetermined minimumvalue of spacing, whereby said shutter selectively blocks communicationbetween said rst waveguide section and said second waveguide sections,permitting communication from said first waveguide section to no morethan one yof said second waveguide sections.

7. A waveguide switching apparatus comprising a first waveguide sectionformed into arcuate shape about a predetermined axis to guideelectromagnetic energy therein along a path corresponding to a portionof a circle, a plurality of openings of equal arcuate extent uniformlyspaced along said path, the arcuate spacing between said openings beingequal to said arcuate extent; a plurality of second waveguide sections,each of said second waveguide sections having an opening in the wallthereof and being rigidly fixed with respect to said first waveguidesection, wherein each of the openings in said second waveguide sectionsregisters with an opening of said first waveguide section; and aconductive shutter adapted for rotation about said axis and disposed formovement between the registering openings of said further waveguidesections and said first waveguide section, said shutter having anopening of arcuate extent equal to that of said first waveguideopenings, whereby said shutter selectively permits communication fromsaid first waveguidesection to no more than one of said second waveguidesections.

f8. A waveguide switching apparatus as in claim 6 wherein saidpredetermined minimum value of arcuate extent is equal to the length ofan opening necessary to transfer all of the electromagnetic energy fromsaid iirst waveguide section to a second waveguide section.

9. A waveguide switching apparatus as in claim 6 wherein said rstwaveguide section includes means to couple electromagnetic energy `intosaid section, said means being connected to said section at oneextremity thereof, and wherein each of said second waveguide sections`includes means to couple electromagnetic energyvout of said secondsection, each ofsaid further output coupling means being connected toone of said second waveguide sections `at one extremity' thereof.

10. A `waveguide switching apparatus as in claim ,6 wherein each of saidwaveguide sections includes means connected at one extremity thereof forcoupling electromagnetic energy to said section, and further in cludes anon-reective dissipative termination disposed in the other extremity ofsaid waveguide section.

References Cited in the le of this patent UNITED STATES PATENTS2,576,943 Jenks Dec. 4, Y1951A 2,735,069 Riblet Feb. 14, 1956 2,762,973Kallmann Sept. 11, 1956

